U.S. Pat. No. 5,011,823 of S. Jin et al. discloses a process for fabricating oxide superconductors by a melt growth method. In this process, a melt is produced from a precursor material which, preferably, is in the form of pressed superconductive oxide powder; the melt is thereafter cooled to form a body of the desired shape, which is then heat-treated.
The process of the Jin et al. patent allows one to make wires, ribbons, and rods by zone melting. However, this process is not readily suitable for making shaped articles which have a relatively large cross-sectional area and/or which have complex shapes.
Some of the disadvantages of the process of the Jin et al. patent are avoided by a process described in U.S. Pat. No. 4,956,336 of K. Salama et al. In the Salama et al. process, a solid state reaction product is compacted and then sintered at a temperature of from about 40 to about 90 degrees Centigrade below its melting point. Thereafter, the product is slowly cooled over a period of a least about 12 hours.
It is an object of this invention to provide a process for producing a bulk superconductive object which has a critical current of at least about 2,000 amperes per square centimeter at 77 degrees Kelvin when subjected a magnetic field of 1 Tesla and which displays flux pinning behavior.
It is another object of this invention to provide a process for preparing a bulk superconductive object with a relatively large cross-sectional area and/or a relatively complex shape.
It is yet another object of this invention to provide a shaped body which may be used to produce a bulk superconductive material.
It is yet another object of this invention to provide a an economical process for making the bulk superconductive material which does not necessarily require a heat treatment for a period of at least 12 hours.
It is yet another object of this invention to provide a shaped object consisting essentially of the textured superconductive material of this invention.